Making… Paint!

Electrolysis of water for side effects

Back in late August, when we did the experimentation with ferrofluids, I discovered-for-myself an interesting process for making the requisite Fe3O4, aka magnetite. Through an electrolysis process, and then some other steps, I was able to create a fair amount of magnetite from iron screws. I ditched this process in regards to ferrofluids, but eventually picked it back up again for making paint pigments.

Yes, real paint is pretty cheap, and there are easier ways to make black pigments, such as carbonizing just about anything (though I don’t know of easier ways to make brown from a scratch process). That wasn’t the point. I specifically wanted to make paintings in which I could claim I made the pigments.

From the time of the Renaissance up to the late 19th century, artists often were engineers and scientists, and vice versa. Leonardo Da Vinci should probably be more accurately remembered as a government contractor in weapons engineering rather than artist. Prior to the industrial revolution, any painter kind of had to be a competent chemists to able to make their pigments. And any student of botany, biology, and other natural sciences needed to be competent sketch artists to be able to record their work.

I strive to maintain a lot of that tradition in my own work, and I think it’s important to know what goes in to the things we make, even if that thing is “just art”.

I started with a beaker full of salt water. Ahem, excuse me, “aqueous solution of sodium chloride”. Right. The sodium chloride acts as an electrolyte to allow the electricity to conduct through the water. Basic stuff here. I’ve got a laptop battery charger with alligator clips holding on to the plug. I have iron screws as both electrodes because I didn’t want to bother making sure I had the right polarity on the charger plug. The screws dangle from wires that are taped to my beaker so they stay in place.

WARNING! This process creates a couple of nasty things. First, there will be a small amount of hydrochloric acid produced in beaker. It won’t be a lot, but if you keep your hands submerged in it for long enough, you could get a slight rash (yes, I speak from experience, from many, many years ago when I accidentally blew up my bedroom as a kid). It also creates small amount of chlorine gas, which is poisonous! For the small scale at which I was working, as well as working in a well-ventilated room, it was not a concern. However, I should have used sodium bicarbonate as the electrolyte, it would have eliminated both of these issues. Alas, I didn’t have any at the time.

It also creates a LARGE amount of hydrogen and oxygen gas, which if you’re dumb like I was when I was 15 and try to collect it, can be quite explosive. You are forewarned!

Iron hydroxide painting

The orange stuff floating in the top of the beaker is iron hydroxide. You might not be able to tell from the picture, but there is a slight green tint to rest of the water. That is also iron hydroxide, in another form. Iron hydroxide is apparently very difficult to control in color. However, I did use a little paint brush to sweep up the orange stuff from the edges of my beaker and make this little painting.

The greenish-black iron hydroxide was what I was after. I actually thought it was the magentite iron oxide that I was looking for at the time, but I’ve since learned otherwise. Black iron hydroxide is slightly magnetic, so I balanced my beaker on top of a large, neodymium magnet to draw the precipitate down to the bottom of my beaker, allowing me to pour most of the water off of the top of the stuff I cared about.

It's kind of like silt

I wanted to boil the rest of the water out, as the leftover looked like diluted ink.  Eventually I was left with a liquid that was quite thick, almost like river mud, meaning it sputtered too much to continue boiling. The material on the edges dried out and turned brown; more on that in a bit. This was at the time we were doing the ferrofluid stuff, so I was very keen on removing the water and replacing it with a very light oil. One of our members suggested using acetone to dissolve with the water and increase the overall volatility, to speed natural evaporation. At the time, I still didn’t know that I only had iron hydroxide, I thought I had iron oxide, so this step was quite serendipitous. Green-black iron hydroxide in anaerobic conditions will oxidize to magnetite! I believe the acetone deoxygenated the water and left water protons for oxidizing the iron hydroxide. It very clearly went from a greenish-black, pluming precipitate to a very black precipitate fell out of suspension very easily and was much more magnetic. It still didn’t make a great ferrofluid (I didn’t have a surfactant, confused emulsifiers with surfactants, got unconfused and tried to use dish soap as my surfactant, and eventually just had a mess everywhere).


But I was intrigued by how dark of a black I had on my hands, and how readily it stained everything it touched (much to our quarter master’s chagrin). At this point, I had something I could start painting with. I mixed a little with some more water because I knew I wanted to do something spattery, and then made this stylistic interpretation of the classic video game “Asteroids”. There is a little bit of a brown tint to it because of an inefficiency in my process, but then I recontextualized and made it part of my process. I made a frame for it out of scrap wood, but I probably should not have. Now it just kind of looks cheesy. Grumble.

I wanted to now take advantage of the brown crust on the edge of my previous boil experiment. I realized that it was actually another form of iron oxide called hematite, Fe2O3. Magnetite oxidizes to hematite in open air under a flame, so I took some of my black material and blasted it under my pipe welding torch. I eventually shattered my shot glass that I was using as an impromptu beaker from overheating. Yet another instance of my lack of preparation and use of proper tools nearly getting me hurt. But I digress.

Steel Bearing

The last painting was difficult to work with because the water took forever to evaporate, which warped the paper I was painting on. This time, I mixed my pigment with acetone. It was more difficult to keep the pigment in suspension, but the much more volatile acetone evaporated much quicker, leaving me with dry paper that didn’t warp. The result was a painting of a steel bearing, which I thought was interesting because I’m technically painting with “rust”.


I finished up with the iron oxide by making an ink with it and this last drawing of the entrance to a mysterious forest.

So now what? Now, I’m experimenting with different metals to see what other colors I can get. I know that copper can lead to some green tints, which I’m very excited to try to replicate. I was able to

Mint-green copper hydroxide

make a very, very small amount of copper hydroxide last night, which you can see in the following pictures. I also made a small amount of yellowish brown copper oxide. Unfortunately, it rather readily oxidizes in air to make black copper oxide, which I’m not too interested in as the black iron oxide is easier to make.

Yellow-brown copper oxide

The brown is nice because it’s not as dark as the brown iron oxide, but I’m excited about the possibility of making green.

Oh, I also made a blue flame.

5 thoughts on “Making… Paint!

  1. dood, ive been using hematite for pigments for a while [pretty much all the range].. Its all been touchy feely with my negligible knowledge in chem,
    Thx for all the closure /:D
    [if yre ever up for a show in the middle east, find me: i got the channels to sell]

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